The technology described herein relates generally to gas turbine engines and more particularly to the control of gas turbine engines for aircraft.
For recent turbofan engines, pressure ratios act as a control parameter to achieve optimal performance and operability. However, pressure ratio tracking with a multivariable or multi-input, multi-output (MIMO) system using a feedback loop may result in undesirable levels of error, limiting the performance of the control system, in particular, in fast transient cases. Solutions to mitigate the effect of the tracking error typically include additional logical and heuristic processes that augment the basic feedback system during transient operation. That is, conventional tracking systems override the MIMO feedback model with additional control schemes based on measurements of how much the reference is changing to account for a fundamental mischaracterization of the underlying system. Essentially, the current solutions for control systems for turbine engines acknowledge the shortcomings of the feedback multivariable system, but do not address the problem directly.
Accordingly, it would be desirable to develop a control system for gas turbine engines that consistently tracks input and output variable states for both small and large transient conditions.